U.S. patent application number 15/351865 was filed with the patent office on 2017-06-15 for apparatus and method for preventing reverse current in dc-dc converter of vehicle.
The applicant listed for this patent is HYUNDAI MOBIS CO., LTD.. Invention is credited to Hyo Jin BANG.
Application Number | 20170170719 15/351865 |
Document ID | / |
Family ID | 59020167 |
Filed Date | 2017-06-15 |
United States Patent
Application |
20170170719 |
Kind Code |
A1 |
BANG; Hyo Jin |
June 15, 2017 |
APPARATUS AND METHOD FOR PREVENTING REVERSE CURRENT IN DC-DC
CONVERTER OF VEHICLE
Abstract
An apparatus and a method for preventing a reverse current in a
DC-DC converter of a vehicle including a measurement portion
configured to measure an output voltage of the DC-DC converter of
the vehicle; a verification portion configured to verify a
difference between the output voltage and a preset reference output
voltage at every preset period; and a controller configured to
control a switch of a synchronous rectification circuit, which is
implemented at a secondary side of a main transformer of the DC-DC
converter, to be in an ON or OFF state according to the difference
between the output voltage and the preset reference output
voltage.
Inventors: |
BANG; Hyo Jin; (Seoul,
KR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
HYUNDAI MOBIS CO., LTD. |
Seoul |
|
KR |
|
|
Family ID: |
59020167 |
Appl. No.: |
15/351865 |
Filed: |
November 15, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B60L 58/20 20190201;
H02M 1/32 20130101; H02P 27/06 20130101; H02M 3/33592 20130101;
H02M 3/33584 20130101; B60L 2210/12 20130101; B60L 2240/526
20130101; Y02T 10/92 20130101; B60L 2210/10 20130101; Y02T 10/70
20130101; H02M 1/38 20130101; Y02T 10/72 20130101 |
International
Class: |
H02M 1/38 20060101
H02M001/38; H02P 27/06 20060101 H02P027/06; B60L 11/18 20060101
B60L011/18; H02M 3/335 20060101 H02M003/335 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 14, 2015 |
KR |
10-2015-0178048 |
Claims
1. An apparatus for preventing a reverse current in a direct
current (DC)-DC converter of a vehicle, comprising: a measurement
portion configured to measure an output voltage of the DC-DC
converter of the vehicle; a verification portion configured to
verify a difference between the output voltage and a preset
reference output voltage at every preset period; and a controller
configured to control a switch of a synchronous rectification
circuit, which is implemented at a secondary side of a main
transformer of the DC-DC converter, to be in an ON or OFF state
according to the difference between the output voltage and the
preset reference output voltage.
2. The apparatus of claim 1, wherein the verification portion
verifies whether a value of the output voltage is less than a value
that is obtained by subtracting a preset error from a value of the
preset reference output voltage.
3. The apparatus of claim 2, wherein the controller is configured
to control the switch of the synchronous rectification circuit to
be in an OFF state when the value of the output voltage is verified
through the verification portion to be less than the value that is
obtained by subtracting the preset error from the value of the
preset reference output voltage.
4. The apparatus of claim 3, wherein the controller is configured
to count up a number of times of operation that the switch of the
synchronous rectification circuit is controlled to be in the OFF
state, and to control the switch to be in the OFF state regardless
of the verification result of the verification portion when the
number of times of operation is equal to or greater than a preset
first number of times.
5. The apparatus of claim 4, wherein the controller is configured
to control a state of the switch by comparing a current supply
voltage of the DC-DC converter, which is determined according to
the output voltage and the preset reference output voltage, with a
prestored previous supply voltage when the value of the output
voltage is verified through the verification portion to be equal to
or greater than the value that is obtained by subtracting the
preset error from the value of the preset reference output
voltage.
6. The apparatus of claim 5, wherein the controller is configured
to control the switch to be in the OFF state when the current
supply voltage is verified to be less than the previous supply
voltage, and to control the switch to be in the ON state when the
current supply voltage is equal to or greater than the previous
supply voltage.
7. The apparatus of claim 5, wherein the controller is configured
to count up a number of times of verification that the value of the
output voltage is verified through the verification portion to be
equal to or greater than the value obtained by subtracting the
preset error from the value of the preset reference output voltage
and the current supply voltage is verified to be less than the
previous supply voltage, and to control the switch to be in the OFF
state when the number of times of verification is greater than a
second number of times and the switch to be in the ON state when
the number of times of verification is equal to or less than the
second number of times.
8. The apparatus of claim 7, wherein the controller is configured
to reset the number of times of verification to 0 when the switch
is controlled to be in the OFF state and the current supply voltage
is verified to be equal to or greater than the previous supply
voltage, and to reset the number of times of operation to 0 when
the switch is controlled to be in the ON state.
9. A method for preventing a reverse current in a DC-DC converter
of a vehicle, comprising: measuring an output voltage of the DC-DC
converter of the vehicle; verifying a difference between the output
voltage and a preset reference output voltage at every preset
period; and controlling a switch of a synchronous rectification
circuit, which is implemented at a secondary side of a main
transformer of the DC-DC converter, to be in an ON or OFF state
according to the difference between the output voltage and the
preset reference output voltage.
10. The method of claim 9, wherein the verifying verifies whether a
value of the output voltage is less than a value that is obtained
by subtracting a preset error from a value of the preset reference
output voltage.
11. The method of claim 9, wherein the controlling controls the
switch of the synchronous rectification circuit to be in an OFF
state when the value of the output voltage is verified in the
verifying to be less than the value that is obtained by subtracting
the preset error from the value of the preset reference output
voltage.
12. The method of claim 11, wherein the controlling counts up a
number of times of operation that the switch of the synchronous
rectification circuit is controlled to be in the OFF state, and
controls the switch to be in the OFF state regardless of the
verification result of the verifying when the number of times of
operation is equal to or greater than a preset first number of
times.
13. The method of claim 12, wherein the controlling controls a
state of the switch by comparing a current supply voltage of the
DC-DC converter, which is determined according to the output
voltage and the preset reference output voltage, with a prestored
previous supply voltage when the value of the output voltage is
verified in the verifying to be equal to or greater than the value
that is obtained by subtracting the preset error from the value of
the preset reference output voltage.
14. The method of claim 13, wherein the controlling controls the
switch to be in the OFF state when the current supply voltage is
verified to be less than the previous supply voltage, and controls
the switch to be in the ON state when the current supply voltage is
equal to or greater than the previous supply voltage.
15. The method of claim 13, wherein the controlling counts up a
number of times of verification that the value of the output
voltage is verified in the verifying to be equal to or greater than
the value obtained by subtracting the preset error from the value
of the preset reference output voltage and the current supply
voltage is verified to be less than the previous supply voltage,
and controls the switch to be in the OFF state when the number of
times of verification is greater than a second number of times and
to be in the ON state when the number of times of verification is
equal to or less than the second number of times.
16. The method of claim 15, further comprising: resetting the
number of times of verification to 0 when the switch is controlled
to be in the OFF state and the current supply voltage is verified
to be equal to or greater than the previous supply voltage, and
resetting the number of times of operation to 0 when the switch is
controlled to be in the ON state.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application claims priority from and the benefit of
Korean Patent Application No. 10-2015-0178048, filed on Dec. 14,
2015, the disclosure of which is incorporated herein by reference
in its entirety.
BACKGROUND
[0002] Field
[0003] Exemplary embodiments of the present disclosure relate to a
direct current (DC)-DC converter of a vehicle, and more
particularly, to an apparatus and a method for preventing a reverse
current in a DC-DC converter of a vehicle, which are capable of
preventing a reverse current from being generated in a DC-DC
converter of a vehicle.
[0004] Discussion of the Background
[0005] A conventional electric power flow of a hybrid vehicle will
be described with reference to FIG. 1.
[0006] FIG. 1 is a diagram for describing an electric power flow of
a battery system of a conventional hybrid vehicle.
[0007] As shown in FIG. 1, when a hybrid vehicle runs normally, an
electric motor is driven by receiving electric power from a high
voltage battery through an inverter.
[0008] The driven electric motor delivers power to a power
distributor to drive an engine so that the hybrid vehicle may run.
A low voltage DC-DC converter (LDC) connected to the high voltage
battery may charge a low voltage battery (a 12 volts (V) battery)
to supply the electric power to low voltage electronic equipment
loads in the hybrid vehicle.
[0009] When the hybrid vehicle reduces speed and runs on a downhill
road (a downward grade) section, a rotational force is generated at
the power distributor. With such a rotational force, the electric
motor may operate as an electric power generator to charge the high
voltage battery through the inverter. At this point, the LDC
connected to the high voltage battery may charge the low voltage
battery the same as when the hybrid vehicle runs normally, thereby
supplying the electric power to the low voltage electronic
equipment loads in the hybrid vehicle.
[0010] A configuration of a DC-DC converter generally provided in a
hybrid vehicle is the same as shown in FIG. 2.
[0011] As shown in FIG. 2, a DC-DC converter 20 may include a high
voltage H-bridge circuit 21 which controls a high voltage to be
applied to a main transformer 22 for a predetermined time, and the
main transformer 22 for an electrical insulation.
[0012] A synchronous rectification circuit 23 is included at a
secondary side of the main transformer 22 to rectify an alternating
current (AC) voltage. At this point, the synchronous rectification
circuit 23 may employ a metal oxide semiconductor field effect
transistor (MOSFET) to increase efficiency of a battery system of a
hybrid vehicle.
[0013] Further, the low voltage (for example, 12V) rectified in the
synchronous rectification circuit 23 is supplied to an electronic
equipment load 25 and a low voltage battery 26 (for example, a 12 V
battery) via an output filter circuit 24.
[0014] In addition, a voltage control device 27 is configured as an
electric power circuit of such a DC-DC converter 20 to control an
output voltage. The voltage control device 27 determines a supply
voltage value V3, which is supplied to the high voltage H-bridge
circuit 21, according to a difference between an output voltage
value V1 of the DC-DC converter 20 and a preset reference output
voltage value V2.
[0015] An output voltage of the DC-DC converter 20 is controlled in
real time according to various conditions of the electronic
equipment load 25 of the hybrid vehicle. When the electronic
equipment load 25 is abruptly changed, there is a need to limit an
output current or output electric power, and a situation may arise
in which the output voltage of the DC-DC converter 20 should be
abruptly decreased. At this point, the reference output voltage
value V2 of the DC-DC converter 20 is adjusted to be low so that a
supply current being supplied to the DC-DC converter 20 may be
small.
[0016] When the output voltage of the DC-DC converter 20 is lower
than that of the low voltage battery 26, the DC-DC converter 20 of
a synchronous rectification type may operate as a bidirectional
DC-DC converter. As a result, a reverse current I.sub.out of
several hundred amperes (A) is generated at the DC-DC converter 20
in a direction as shown in FIG. 3A. For example, as a simulation
result shown in FIG. 3B, when the reference output voltage value V2
of the DC-DC converter 20 is abruptly varied, a reverse current
I.sub.out of about 600 A flows at the DC-DC converter 20. Such
generation of the reverse current induces burning of a circuit and
is also a cause of shortening a battery lifespan.
SUMMARY
[0017] Exemplary embodiments of the present invention provide an
apparatus and a method for preventing a reverse current in a DC-DC
converter of a vehicle by verifying a condition in which the
reverse current is generated and then blocking in advance a cause
of the reverse current.
[0018] The technical objectives of the inventive concept are not
limited to the above disclosure; other objectives may become
apparent to those of ordinary skill in the art based on the
following descriptions.
[0019] An exemplary embodiment of the present invention discloses
an apparatus for preventing a reverse current in a direct current
(DC)-DC converter of a vehicle, including a measurement portion
configured to measure an output voltage of the DC-DC converter of
the vehicle; a verification portion configured to verify a
difference between the output voltage and a preset reference output
voltage at every preset period; and a controller configured to
control a switch of a synchronous rectification circuit to be in an
ON or OFF state according to the difference between the output
voltage and the preset reference output voltage, which is
implemented at a secondary side of a main transformer of the DC-DC
converter.
[0020] An exemplary embodiment of the present invention discloses a
method for preventing a reverse current in a DC-DC converter of a
vehicle, including: measuring an output voltage of the DC-DC
converter of the vehicle; verifying a difference between the output
voltage and a preset reference output voltage at every preset
period; and controlling a switch of a synchronous rectification
circuit, which is implemented at a secondary side of a main
transformer of the DC-DC converter, to be in an ON or OFF state
according to the difference between the output voltage and the
preset reference output voltage.
[0021] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory and are intended to provide further explanation of
the claimed subject matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] The accompanying drawings, which are included to provide a
further understanding of the invention and are incorporated in and
constitute a part of this specification, illustrate embodiments of
the invention, and together with the description serve to explain
the principles of the invention.
[0023] FIG. 1 is a diagram illustrating an electric power flow of a
battery system of a conventional hybrid vehicle.
[0024] FIG. 2 is a diagram illustrating a circuit configuration of
a direct current (DC)-DC converter provided in a conventional
hybrid vehicle.
[0025] FIG. 3A and FIG. 3B are reference diagrams for describing a
reverse current of the DC-DC converter of the conventional hybrid
vehicle, respectively.
[0026] FIG. 4 is an entire circuit configuration diagram of a DC-DC
converter including a reverse current prevention apparatus
according to an exemplary embodiment.
[0027] FIG. 5 is a block diagram illustrating a configuration with
respect to the reverse current prevention apparatus of the DC-DC
converter in a vehicle according to an exemplary embodiment.
[0028] FIG. 6 is a diagram illustrating a simulation result of a
situation in which a switch of a synchronous rectification circuit
is controlled to be in an OFF state in Mode 2 according to an
exemplary embodiment.
[0029] FIG. 7 is a diagram illustrating voltage level variation of
each of an output voltage of the DC-DC converter, a reference
output voltage, and a supply voltage according to a state control
of the switch of the synchronous rectification circuit in Mode 1
and Mode 2 according to an exemplary embodiment.
[0030] FIG. 8 is an operational flow chart of a reverse current
prevention method of the DC-DC converter of the vehicle according
to an exemplary embodiment.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0031] Hereinafter, exemplary embodiments of the present invention
will be described in detail with reference to the accompanying
drawings. Throughout the specification, like reference numerals
denote like elements having the same or similar functions. Detailed
description of components or functions apparent to those skilled in
the art will be omitted for clarity. It should be understood that
the following exemplary embodiments are provided by way of example
and that the present invention is not limited to the exemplary
embodiments disclosed herein and can be implemented in different
forms by those skilled in the art. It should be noted that the
drawings are not to precise scale and may be exaggerated in
thickness of lines or sizes of components for descriptive
convenience and clarity only.
[0032] The terminology used herein is for the purpose of describing
particular embodiments only and is not intended to be limiting of
the disclosure. As used herein, the singular forms "a," "an" and
"the" are intended to include the plural forms as well, unless the
context clearly indicates otherwise. It should be further
understood that the terms "comprises," "comprising," "includes,"
and/or "including," when used herein, specify the presence of
stated features, integers, steps, operations, elements, and/or
components, but do not preclude the presence or addition of one or
more other features, integers, steps, operations, elements,
components, and/or groups thereof.
[0033] Unless defined otherwise, it is to be understood that all
the terms (including technical and scientific terms) used in the
specification has the same meaning as those that are understood by
those who skilled in the art. Further, the terms defined by the
dictionary generally used should not be ideally or excessively
formally defined unless clearly defined specifically. It will be
understood that for purposes of this disclosure, "at least one of
X, Y, and Z" can be construed as X only, Y only, Z only, or any
combination of two or more items X, Y, and Z (e.g., XYZ, XYY, YZ,
ZZ). Unless particularly described to the contrary, the term
"comprise", "configure", "have", or the like, which are described
herein, will be understood to imply the inclusion of the stated
components, and therefore should be construed as including other
components, and not the exclusion of any other elements.
[0034] The present invention relates to a technology for preventing
a reverse current from being generated in a DC-DC converter of a
vehicle. An exemplary direct current (DC)-DC converter including a
reverse current prevention apparatus applicable to the present
invention will be described below. The exemplary direct current
(DC)-DC converter including a reverse current prevention apparatus
may be used with one or more of the various exemplary
embodiments.
[0035] FIG. 4 is an entire circuit configuration diagram of a DC-DC
converter including a reverse current prevention apparatus
according to an exemplary embodiment.
[0036] As shown in FIG. 4, a DC-DC converter 100 including a
reverse current prevention apparatus according to the exemplary
embodiment may include a high voltage H-bridge circuit 110 which
controls a high voltage to be applied to a main transformer 120 for
a predetermined time, and the main transformer 120 for an
electrical insulation.
[0037] A synchronous rectification circuit 130 may be included at a
secondary side of the main transformer 120 to rectify an
alternating current (AC) voltage.
[0038] The synchronous rectification circuit 130 may employ a power
switch 131 (for example, a metal oxide semiconductor field effect
transistor (MOSFET), that is, a synchronous rectification (SR)
switch) to increase efficiency of a battery system of a vehicle. A
low voltage (for example, 12 volts (V)) rectified in the
synchronous rectification circuit 130 is supplied to an electronic
equipment load 150 and a low voltage battery 160 (for example, a 12
V battery) via an output filter circuit 140.
[0039] In addition, a voltage control device 170 is configured at
an electric power circuit of such a DC-DC converter 100 to control
an output voltage thereof. The voltage control device 170
determines a supply voltage value V3, which is supplied to the high
voltage H-bridge circuit 110, according to a difference between an
output voltage value V1 of the DC-DC converter 100 and a preset
reference output voltage value V2. Here, the reference output
voltage value V2 is an output voltage reference of the DC-DC
converter 100 for an eco-friendly vehicle, and generally, may be
set to a voltage (for example, 13.9 V) higher than that of the low
voltage battery 160. For example, a maximum value of the reference
output voltage value V2 may be 15.1 V, and a minimum value thereof
may be determined to the output voltage value V1 when a value
obtained by subtracting the reference output voltage value V2 from
the output voltage value V1 is greater than 0.5 V.
[0040] In particular, the voltage control device 170 compares the
output voltage value V1 of the DC-DC converter 100 with the
reference output voltage value V2, and then transmits a signal of
the supply voltage value V3 to the high voltage H-bridge circuit
110. Consequently, according to a level of the supply voltage value
V3, a time for applying an AC voltage from the high voltage
H-bridge circuit 110 to the main transformer 120 is determined.
[0041] The output voltage value V1 of the DC-DC converter 100 is
controlled in real time according to various conditions of the
electronic equipment load 150 of a vehicle. For example, when the
electronic equipment load 150 is abruptly changed, there is a need
to limit an output current or output electric power, and a
situation may arise in which an output voltage of the DC-DC
converter 100 should be abruptly decreased. At this point, the
reference output voltage value V2 of the DC-DC converter 100 is
adjusted to be a low value so that a supply current being supplied
to the DC-DC converter 100 may be low. When the reference output
voltage value V2 is abruptly decreased for the purpose of limiting
an abrupt voltage or an abrupt current, an output voltage Vout of
the DC-DC converter 100 is to be lowered than a voltage Vbat of the
low voltage battery 160, and thus, a reverse current of several
hundred amperes (A) may be generated.
[0042] Therefore, the DC-DC converter 100 according to an exemplary
embodiment further includes a reverse current prevention apparatus
180. The reverse current prevention apparatus 180 according to an
exemplary embodiment verifies the output voltage value V1 of the
DC-DC converter 100, the reference output voltage value V2 thereof,
and the supply voltage value V3 determined according to a
difference between the output voltage value V1 of the DC-DC
converter 100 and the reference output voltage value V2 thereof,
and controls the switch 131 (MOSFET) of the synchronous
rectification circuit 130 to be in an ON or OFF state to prevent a
reverse current from being generated in the DC-DC converter
100.
[0043] Hereinafter, a reverse current prevention technique of the
DC-DC converter of the vehicle according to an exemplary embodiment
will be described in detail with reference to FIGS. 5 and 8.
[0044] FIG. 5 is a block diagram of the reverse current prevention
apparatus of the DC-DC converter of the vehicle according to an
exemplary embodiment.
[0045] As shown in FIG. 5, the reverse current prevention apparatus
180 of the DC-DC converter of the vehicle includes a measurement
portion 181, a verification portion 182, and a controller 183.
[0046] The measurement portion 181 measures the output voltage
value V1 of the DC-DC converter 100. At this point, the measurement
portion 181 may be a voltage sensor which is provided at a
predetermined position of a circuit of the DC-DC converter 100 to
measure a voltage output therefrom.
[0047] The verification portion 182 compares the output voltage
value V1 of the DC-DC converter 100 measured at the measurement
portion 181 with the preset reference output voltage value V2. At
this point, the verification portion 182 verifies whether the
output voltage value V1 of the DC-DC converter 100 is less than the
reference output voltage value V2 (that is, V1<V2).
[0048] At this point, the verification portion 182 may compare the
output voltage value V1 of the DC-DC converter 100 with the preset
reference output voltage value V2 at every preset period.
[0049] Preferably, the verification portion 182 may compare the
output voltage value V1 of the DC-DC converter 100 with the
reference output voltage value V2 by considering a certain error
value. Here, the error value is a preset value and may be changed
by a developer and the like.
[0050] In particular, the verification portion 182 compares a value
obtained by subtracting a preset error value (for example, 0.2 V)
from the reference output voltage value V2 with the output voltage
value V1 of the DC-DC converter 100, and verifies whether the
output voltage value V1 of the DC-DC converter 100 is less than the
obtained value (that is, V1<V2-0.2). In an exemplary embodiment
of the present disclosure, a situation will be described below in
which voltage values are compared with each other in consideration
of an error value.
[0051] When the output voltage value V1 of the DC-DC converter 100
is verified to be less than the value obtained by subtracting the
error value 0.2 V from the reference output voltage value V2 (that
is, V1<V2-0.2) based on the verification result of the
verification portion 182, the controller 183 controls the switch
131 of the synchronous rectification circuit 130 to be in an OFF
state. In particular, when the output voltage value V1 of the DC-DC
converter 100 is verified to be less than the value obtained by
subtracting the error value 0.2 V from the reference output voltage
value V2 (that is, V1<V2-0.2), the controller 183 determines
that there may be possibility of generation of a reverse current at
the DC-DC converter 100 and controls the switch 131 of the
synchronous rectification circuit 130 to be in the OFF state to
prevent the reverse current from being generated. Hereinafter, such
an operation will be referred to as a control operation according
to Mode 1.
[0052] When controlling the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state according to Mode
1 (that is, it is determined to be less than the value obtained by
subtracting the error value 0.2 V from the reference output voltage
value V2), the controller 183 counts up a number of times of
operation N with respect to such operations. That is, based on the
verification result of the verification portion 182 at every preset
period, the controller 183 may count up and accumulate the number
of times of operation N whenever controlling the switch 131 of the
synchronous rectification circuit 130 to be in an OFF state
according to Mode 1 (that is, N=N+1).
[0053] In addition, the controller 183 stores a value (a variation
amount of a supply voltage, that is, .DELTA.V=V3-V3_old), which is
obtained by subtracting a prestored previous supply voltage value
V3_old from a supply voltage value V3 that is determined through a
current output voltage value V1 of the DC-DC converter 100 and the
reference output voltage value V2 thereof, in a separate memory.
When a previous variation amount of the supply voltage .DELTA.V_old
has been stored in the separate memory, the controller 183 stores
the variation amount of the supply voltage .DELTA.V which is
currently obtained at the previous variation amount of the supply
voltage .DELTA.V_old (that is, .DELTA.V_old=.DELTA.V).
[0054] When the counted number of times of operation N is less than
a preset number of times (a first number of times) X, the
controller 183 controls the switch 131 of the synchronous
rectification circuit 130 to be in an ON or OFF state based on the
verification result of the verification portion 182 at every preset
period. Here, the first number of times X may be set and changed by
a developer in advance. Also, the first number of times X may be
set in consideration of a battery system of a vehicle that is
verified through a pre-experiment, and specifically, in
consideration of a result value that is obtained by dividing a
transient response time is of the DC-DC converter 100 by a control
period (a preset period).
[0055] When the number of times of operation N is equal to or
greater than the preset first number of times X, the controller 183
controls the switch 131 of the synchronous rectification circuit
130 to be in the OFF state regardless of the verification result of
the verification portion 182. The reason for that is that the
battery system of the vehicle may be determined to be in a
transient state (that is, a state in which a balance state of an
electric power system could not be maintained any more due to
generation of disturbance such as variation of a load or a line
accident) when a number of times of operations N that the output
voltage value V1 of the DC-DC converter 100 is verified through the
verification portion 182 to be less than the value obtained by
subtracting the error value 0.2 V from the reference output voltage
value V2 is equal to or greater than the preset first number of
times X.
[0056] The controller 183 determines the previous supply voltage
value V3_old to a current supply voltage value V3 (that is,
V3_old=V3) that is calculated using a currently measured output
voltage value V1 of the DC-DC converter 100 and a currently set
reference output voltage value V2 thereof. At this point, the
determined previous supply voltage value V3_old may be stored in
the separate memory, and the stored previous supply voltage value
V3_old may be stored without being deleted even when electric power
is blocked (for example, starting of a vehicle is turned off).
[0057] In addition, the controller 183 stores a value (a variation
amount of the supply voltage, that is, .DELTA.V=V3-V3_old), which
is obtained by subtracting the prestored previous supply voltage
value V3_old from the supply voltage value V3 determined through
the current output voltage value V1 of the DC-DC converter 100 and
the reference output voltage value V2 thereof, in the separate
memory. When the previous variation amount of the supply voltage
.DELTA.V_old has been stored in the separate memory, the controller
183 stores the currently obtained variation amount of the supply
voltage .DELTA.V at the previous variation amount of the supply
voltage .DELTA.V_old (that is, .DELTA.V_old=.DELTA.V).
[0058] Through such a process, when a reverse current of the DC-DC
converter 100 is considered to be generated, the controller 183 may
control the switch 131 of the synchronous rectification circuit 130
to be in the OFF state so that possibility of generation of the
reverse current of the DC-DC converter 100 may be prevented in
advance.
[0059] When the output voltage value V1 of the DC-DC converter 100
is verified to be equal to or greater than the value obtained by
subtracting the error value 0.2 V from the reference output voltage
value V2 based on the verification result of the verification
portion 182 (that is, V1.gtoreq.V2-0.2), the controller 183
compares the current supply voltage value V3 with the previous
supply voltage value V3_old. The reason for this is that when the
output voltage value V1 of the DC-DC converter 100 is verified to
be equal to or greater than the value obtained by subtracting the
error value 0.2 V from the reference output voltage value V2 (that
is, V1.gtoreq.V2-0.2), a situation results in which a reverse
current is not generated at the DC-DC converter 100 according to
the comparison result of the current output voltage value V1 and
the reference output voltage value V2. However, a situation may
arise in which the switch 131 of the synchronous rectification
circuit 130 should be controlled to be in an ON or OFF state for
the reason described below.
[0060] Generally, a difference exists between the reference output
voltage value V2 and an output voltage (that is, Vout=V1) of the
DC-DC converter 100, wherein the reference output voltage value V2
is a reference value that is varied according to a situation of a
system. Here, when the reference value V2 is instantaneously
varied, the output voltage Vout converges on the reference output
voltage value V2. Consequently, the switch 131 of the synchronous
rectification circuit 130 should be controlled to be in the OFF
state when a value obtained by subtracting a preset error value
from the reference output voltage value V2 is controlled to be
greater than the output voltage value V1, but when a value obtained
by subtracting the preset error value from the reference output
voltage value V2 is controlled to be equal to or less than the
output voltage value V1, a state of the switch 131 of the
synchronous rectification circuit 130 should be controlled through
the verification process once more instead of unconditionally
controlling the switch 131 of the synchronous rectification circuit
130 to be in the OFF state.
[0061] In particular, when the output voltage value V1 of the DC-DC
converter 100 is verified to be equal to or greater than the value
obtained by subtracting the error value 0.2 V from the reference
output voltage value V2 (that is, V1.gtoreq.V2-0.2), the controller
183 compares the current supply voltage value V3, which is
determined according to a difference between the output voltage
value V1 of the DC-DC converter 100 and the reference output
voltage value V2 thereof, with the previously (shortly before)
determined supply voltage value V3_old.
[0062] When the current supply voltage value V3 is verified to be
less than the previous supply voltage value V3_old, the controller
183 may control the switch 131 of the synchronous rectification
circuit 130 to be in the OFF state. That is, when the verification
portion 182 verifies that the output voltage value V1 of the DC-DC
converter 100 is equal to or greater than the value obtained by
subtracting the error value 0.2 V from the reference output voltage
value V2 (that is, V1.gtoreq.V2-0.2) and that the current supply
voltage value V3 is less than the previous supply voltage value
V3_old (that is, V3<V3_old), the controller 183 may control the
switch 131 of the synchronous rectification circuit 130 to be in
the OFF state.
[0063] At this point, the controller 183 determines the previous
supply voltage value V3_old to the current supply voltage value V3
calculated using the currently measured output voltage value V1 of
the DC-DC converter 100 and the currently set reference output
voltage value V2 thereof (that is, V3_old=V3), and counts up the
number of times of operation N (that is, N=N+1).
[0064] In addition, the controller 183 stores a value (a variation
amount of the supply voltage, that is, .DELTA.V=V3-V3_old), which
is obtained by subtracting the prestored previous supply voltage
value V3_old from the supply voltage value V3 determined through
the current output voltage value V1 of the DC-DC converter 100 and
the reference output voltage value V2 thereof, in the separate
memory. When a previous variation amount of the supply voltage
.DELTA.V_old has been stored in the separate memory, the controller
183 stores the currently obtained variation amount of the supply
voltage .DELTA.V at the previous variation amount of the supply
voltage .DELTA.V_old (that is, .DELTA.V_old=.DELTA.V).
[0065] After the verification portion 182 verifies that the output
voltage value V1 of the DC-DC converter 100 is equal to or greater
than the value obtained by subtracting the error value 0.2 V from
the reference output voltage value V2 (that is, V1.gtoreq.V2-0.2),
the controller 183 may determine whether to control the switch 131
of the synchronous rectification circuit 130 to be in an OFF state
or an ON state according to a number of times the current supply
voltage value V3 is verified to be less than the previous supply
voltage value V3_old (that is, V3<V3_old).
[0066] In particular, when the current supply voltage value V3 is
verified to be less than the previous supply voltage value V3_old
(that is, V3<V3_old) based on the comparison result, the
controller 183 counts up the number of times (the number of times
of verification) that the verification portion 182 verifies that
the current supply voltage value V3 is less than the previous
supply voltage value V3_old (that is, Y=Y+1). That is, when the
verification portion 182 verifies that the output voltage value V1
of the DC-DC converter 100 is equal to or greater than the value
obtained by subtracting the error value 0.2 V from the reference
output voltage value V2 (that is, V1.gtoreq.V2-0.2), the controller
183 may count up and accumulate the number of times of verification
Y whenever the current supply voltage value V3 is verified to be
less than the previous supply voltage value V3_old (that is,
V3<V3_old).
[0067] Further, it is verified whether the counted number of times
of verification Y (that is, the accumulated number of times that
the output voltage value V1 of the DC-DC converter 100 is verified
to be equal to or greater than the value obtained by subtracting
the error value 0.2 V from the reference output voltage value V2,
and the current supply voltage value V3 is verified to be less than
the previous supply voltage value V3_old) exceeds a preset number
of times (a second number of times) Z (that is, Y>Z). Here, the
second number of times Z is a preset value, and may be varied
according to a response characteristic of a product (a vehicle
battery system or a DC-DC converter of a vehicle battery system)
and may be preset and changed in advance so as to recognize a
voltage drop.
[0068] When the number of times of verification Y exceeds the
second number of times Z (that is, Y>Z), the controller 183
controls the switch 131 of the synchronous rectification circuit
130 to be in the OFF state. That is, when the accumulated number of
times of verification Y that the output voltage value V1 of the
DC-DC converter 100 is verified to be equal to or greater than the
value obtained by subtracting the error value 0.2 V from the
reference output voltage value V2 (V1.gtoreq.V2-0.2) and the
current supply voltage value V3 is verified to be less than the
previous supply voltage value V3_old through the verification
portion 182 exceeds the second number of times Z (that is, Y>Z),
the controller 183 controls the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state. Hereinafter, such
an operation will be referred to as a control operation according
to Mode 2. As described above, when the switch 131 of the
synchronous rectification circuit 130 is controlled to be in the
OFF state according to Mode 2, an output current of the DC-DC
converter 100, a current of the low voltage battery 160, the output
voltage value V1 of the DC-DC converter 100, the reference output
voltage value V2, and the supply voltage value V3 may be varied as
shown in FIG. 6.
[0069] At this point, when controlling the switch 131 of the
synchronous rectification circuit 130 to be in the OFF state
according to Mode 2, the controller 183 determines the previous
supply voltage value V3_old to a current supply voltage value V3
that is calculated using a currently measured output voltage value
V1 of the DC-DC converter 100 and a currently set reference output
voltage value V2 thereof (that is, V3_old=V3), and then resets the
number of times of verification Y to 0.
[0070] In addition, the controller 183 stores a value (a variation
amount of the supply voltage, that is, .DELTA.V=V3-V3_old), which
is obtained by subtracting the prestored previous supply voltage
value V3_old from the supply voltage value V3 that is determined
through the current output voltage value V1 of the DC-DC converter
100 and the reference output voltage value V2, in the separate
memory. When a previous variation amount of the supply voltage
.DELTA.V_old has been stored in the separate memory, the controller
183 stores the currently obtained variation amount of the supply
voltage .DELTA.V at the previous variation amount of the supply
voltage .DELTA.V_old (that is, .DELTA.V_old=.DELTA.V).
[0071] When the current supply voltage value V3 is verified to be
equal to or greater than the previous supply voltage value V3_old
(that is, V3.gtoreq.V3_old) on the basis of the comparison result
of the current supply voltage value V3 and the previous supply
voltage value V3_old, the controller 183 controls the switch 131 of
the synchronous rectification circuit 130 to be in an ON state.
That is, the controller 183 maintains the ON state when the switch
131 of the synchronous rectification circuit 130 is previously in
the ON state, whereas it switches the OFF state to the ON state
when the switch 131 of the synchronous rectification circuit 130 is
previously in the OFF state.
[0072] At this point, the controller 183 determines the previous
supply voltage value V3_old to the current supply voltage value V3
that is calculated using the currently measured output voltage
value V1 of the DC-DC converter 100 and the currently set reference
output voltage value V2 thereof (that is, V3_old=V3). Also, the
controller 183 resets the number of times of operation N and the
number of times of verification Y to 0, respectively.
[0073] In addition, the controller 183 stores a value (a variation
amount of the supply voltage, that is, .DELTA.V=V3-V3_old), which
is obtained by subtracting the prestored previous supply voltage
value V3_old from the supply voltage value V3 that is determined
through the current output voltage value V1 of the DC-DC converter
100 and the reference output voltage value V2, in the separate
memory. When a previous variation amount of the supply voltage
.DELTA.V_old has been stored in the separate memory, the controller
183 stores the currently obtained variation amount of the supply
voltage .DELTA.V at the previous variation amount of the supply
voltage .DELTA.V_old (that is, .DELTA.V_old=.DELTA.V).
[0074] When the current supply voltage value V3 is verified to be
less than the previous supply voltage value V3_old (that is,
V3<V3_old) on the basis of the comparison result of the current
supply voltage value V3 and the previous supply voltage value
V3_old to count up (accumulate) the number of times of verification
Y, and the counted (accumulated) number of times of verification Y
is equal to or less than the second number of times Z, the
controller 183 controls the switch 131 of the synchronous
rectification circuit 130 to be in the ON state. Similarly, in this
case, the controller 183 determines the previous supply voltage
value V3_old to the current supply voltage value V3 that is
calculated using the currently measured output voltage value V1 of
the DC-DC converter 100 and the currently set reference output
voltage value V2 thereof (that is, V3_old=V3), and resets the
number of times of operation N being counted until now to 0.
[0075] Further, the controller 183 stores a value (a variation
amount of the supply voltage, that is, .DELTA.V=V3-V3_old), which
is obtained by subtracting the prestored previous supply voltage
value V3_old from the supply voltage value V3 that is determined
through the current output voltage value V1 of the DC-DC converter
100 and the reference output voltage value V2 thereof, in the
separate memory. When a previous variation amount of the supply
voltage .DELTA.V_old has been stored in the separate memory, the
controller 183 stores the currently obtained variation amount of
the supply voltage .DELTA.V at the previous variation amount of the
supply voltage .DELTA.V_old (that is, .DELTA.V_old=.DELTA.V).
[0076] Through the above described process, the controller 183 may
adaptively control the switch 131 of the synchronous rectification
circuit 130 to be in the OFF or ON state using the output voltage
value V1 of the DC-DC converter 100, the reference output voltage
value V2 thereof, and the supply voltage value V3. For example,
voltage levels of the output voltage value V1 of the DC-DC
converter 100, the reference output voltage value V2 thereof, and
the supply voltage value V3 may be shown as in FIG. 7 according to
a state control of the switch 131 of the synchronous rectification
circuit 130 in Mode 1 and Mode 2.
[0077] As described above, in accordance with an exemplary
embodiment, generation of a reverse current in a DC-DC converter of
a vehicle may be prevented by verifying in advance a condition in
which the reverse current is generated and blocking a cause related
thereto using variables that could be verified through a
conventional sensing circuit of the DC-DC converter of a
synchronous rectification type in the vehicle.
[0078] Moreover, in accordance with an exemplary embodiment, a
separate hardware circuit is not added or changed and a sensor for
sensing a reverse current is omitted so as to prevent a reverse
current in a DC-DC converter of a vehicle so that the number of
components may be reduced to realize reduction of manufacturing
costs, a simplified process, and weight reduction.
[0079] FIG. 8 is a flow chart of a reverse current prevention
method in a DC-DC converter of a vehicle according to an exemplary
embodiment of the present invention.
[0080] Hereinafter, unless specifically noted, steps S810 to S870
are considered as being performed in the reverse current prevention
apparatus 180 of the DC-DC converter implemented at the battery
system of the vehicle.
[0081] First, the reverse current prevention apparatus 180 verifies
whether a number of times N (a number of times of operations) that
the switch 131 of the synchronous rectification circuit 130 is
forcibly controlled to be in an OFF state is equal to or less than
a preset first number of times X in Step S810. Hereinafter, the
number of times of operation N and the preset first number of times
X will be described in detail through the following operation
description.
[0082] When the number of times of operation N is less than the
first number of times X, the reverse current prevention apparatus
180 compares a value, which is obtained by subtracting a preset
error value (for example, 0.2 V) from a reference output voltage
value V2, with an output voltage value V1 of the DC-DC converter
100, and verifies whether the output voltage value V1 of the DC-DC
converter 100 is small, that is, V1<V2-0.2 in Step S820. Here,
the error value is a preset value, and may be changed by a
developer and the like. At this point, the reverse current
prevention apparatus 180 may compare the output voltage value V1 of
the DC-DC converter 100 with the reference output voltage value V2
that is preset, at every preset period.
[0083] Based on the verification result in Step S820, when the
output voltage value V1 of the DC-DC converter 100 is verified to
be less than the value that is obtained by subtracting the error
value 0.2 V from the reference output voltage value V2 (that is,
V1<V2-0.2), the reverse current prevention apparatus 180
controls the switch 131 (for example, an SR Switch) of the
synchronous rectification circuit 130 to be in an OFF state in Step
S830. In particular, when the output voltage value V1 of the DC-DC
converter 100 is verified to be less than the value that is
obtained by subtracting the error value 0.2 V from the reference
output voltage value V2 (that is, V1<V2-0.2), the reverse
current prevention apparatus 180 determines that there is
possibility of generation of a reverse current at the DC-DC
converter 100 to control the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state, thereby
preventing the generation of the reverse current. Hereinafter, such
an operation will be referred to as a control operation according
to Mode 1.
[0084] When controlling the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state according to Mode
1 (that is, it is verified as being less than the value that is
obtained by subtracting the error value 0.2 V from the reference
output voltage value V2), the reverse current prevention apparatus
180 counts up the number of times of operation N with respect to
such an operation. That is, on the basis of the verification result
in Step S820 at every preset period, the reverse current prevention
apparatus 180 may count up and accumulate the number of times of
operation N (that is, N=N+1) whenever controlling the switch 131 of
the synchronous rectification circuit 130 to be in the OFF state
according to Mode 1.
[0085] The reverse current prevention apparatus 180 determines a
previous supply voltage value V3_old to a current supply voltage
value V3 that is calculated using a currently measured output
voltage value V1 of the DC-DC converter 100 and a currently set
reference output voltage value V2 (that is, V3_old=V3). At this
point, the determined previous supply voltage value V3_old may be
stored in a separate memory, and the stored previous supply voltage
value V3_old may be stored in the separate memory without being
deleted therefrom even when electric power is blocked (for example,
starting of a vehicle is turned off).
[0086] In addition, the reverse current prevention apparatus 180
stores a value (a variation amount of the supply voltage, that is,
.DELTA.V=V3-V3_old), which is obtained by subtracting the prestored
previous supply voltage value V3_old from the supply voltage value
V3 that is determined through the current output voltage value V1
of the DC-DC converter 100 and the reference output voltage value
V2 thereof, in the separate memory. When the previous variation
amount of the supply voltage .DELTA.V_old has been stored in the
separate memory, the controller 183 stores the variation amount of
the supply voltage .DELTA.V being currently obtained at the
previous variation amount of the supply voltage .DELTA.V_old (that
is, .DELTA.V_old=.DELTA.V).
[0087] Through such a process, when a reverse current of the DC-DC
converter 100 is considered to be generated, the reverse current
prevention apparatus 180 may control the switch 131 of the
synchronous rectification circuit 130 to be in the OFF state so
that possibility of generation of the reverse current of the DC-DC
converter 100 may be prevented in advance.
[0088] After controlling the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state, the reverse
current prevention apparatus 180 feeds back to Step S810, and
controls the switch 131 of the synchronous rectification circuit
130 to be in an ON or OFF state according to the verification
result in Step S820 at every preset period when the counted number
of times of operation N is less than a preset number of times (a
first number of times) X. Here, the first number of times X may be
set and changed by a developer in advance. Also, the first number
of times X may be set in consideration of a battery system of a
vehicle that is verified through a pre-experiment, and
specifically, in consideration of a result value obtained by
dividing a transient response time is of the DC-DC converter 100 by
a control period (a predetermined period).
[0089] When the number of times of operation N is equal to or
greater than the preset first number of times X based on the
verification result in Step S810, the reverse current prevention
apparatus 180 performs Step S830 in which the switch 131 of the
synchronous rectification circuit 130 is controlled to be in the
OFF state instead of performing Step S820. The reason for that is
that the battery system of the vehicle may be determined to be in a
transient state (that is, a state in which a balance state of an
electric power system could not be maintained any more due to
generation of disturbance such as variation of a load or a line
accident) when the number of times of operation N that the output
voltage value V1 of the DC-DC converter 100 is verified to be less
than the value obtained by subtracting the error value 0.2 V from
the reference output voltage value V2 is equal to or greater than
the preset first number of times X. Meanwhile, when the output
voltage value V1 of the DC-DC converter 100 is verified to be equal
to or greater than the value obtained by subtracting the error
value 0.2 V from the reference output voltage value V2 (that is,
V1.gtoreq.V2-0.2) on the basis of the verification result in Step
S820, the reverse current prevention apparatus 180 compares the
current supply voltage value V3 with the previous supply voltage
value V3_old in Operation S840.
[0090] The reason for that is that when the output voltage value V1
of the DC-DC converter 100 is verified to be equal to or greater
than the value obtained by subtracting the error value 0.2 V from
the reference output voltage value V2 (that is, V1.gtoreq.V2-0.2),
this is a situation in which a reverse current is not generated at
the DC-DC converter 100 according to the comparison result of the
current output voltage value V1 and the reference output voltage
value V2, but there may occur a situation in which the switch 131
of the synchronous rectification circuit 130 should be controlled
to be in an ON or OFF state due to the following reason.
[0091] Generally, a difference exists between the reference output
voltage value V2 and an output voltage (that is, Vout=V1) of the
DC-DC converter 100, wherein the reference output voltage value V2
is a reference value that is varied according to a situation of a
system. Here, when the reference value V2 is instantaneously
varied, the output voltage Vout converges on the reference output
voltage value V2. Consequently, the switch 131 of the synchronous
rectification circuit 130 should be unconditionally controlled to
be in the OFF state when a value obtained by subtracting a preset
error value from the reference output voltage value V2 is
controlled to be greater than the output voltage value V1, but when
a value obtained by subtracting the preset error value from the
reference output voltage value V2 is controlled to be equal to or
less than the output voltage value V1, a state of the switch 131 of
the synchronous rectification circuit 130 should be controlled
through the verification process once more instead of
unconditionally controlling the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state.
[0092] In particular, when the output voltage value V1 of the DC-DC
converter 100 is verified to be equal to or greater than the value
obtained by subtracting the error value 0.2 V from the reference
output voltage value V2 (that is, V1.gtoreq.V2-0.2) based on the
verification result in Step S820, the current supply voltage value
V3, which is determined according to a difference between the
output voltage value V1 of the DC-DC converter 100 and the
reference output voltage value V2 thereof, is compared with the
previously (shortly before) determined supply voltage value
V3_old.
[0093] When the current supply voltage value V3 is verified to be
less than the previous supply voltage value V3_old on the basis of
the verification result in Operation S840, the reverse current
prevention apparatus 180 counts up a number of times (a number of
times of verification) that the current supply voltage value V3 is
verified to be less than the previous supply voltage value V3_old
(that is, Y=Y+1) in Operation S850. That is, when the output
voltage value V1 of the DC-DC converter 100 is verified to be equal
to or greater than the value obtained by subtracting the error
value 0.2 V from the reference output voltage value V2 (that is,
V1.gtoreq.V2-0.2), the reverse current prevention apparatus 180 may
count up and accumulate the number of times of verification Y
whenever the current supply voltage value V3 is verified to be less
than the previous supply voltage value V3_old (that is,
V3<V3_old).
[0094] Further, it is verified whether the counted number of times
of verification Y (that is, the accumulated number of times that
the output voltage value V1 of the DC-DC converter 100 is verified
to be equal to or greater than the value obtained by subtracting
the error value 0.2 V from the reference output voltage value V2,
and the current supply voltage value V3 is verified to be less than
the previous supply voltage value V3_old) exceeds a preset number
of times (a second number of times) Z (that is, Y>Z) in Step
S860. Here, the second number of times Z is a preset value, and may
be varied according to a response characteristic of a product (a
vehicle battery system or a DC-DC converter of a vehicle battery
system) and may be preset and changed in advance so as to recognize
a voltage drop.
[0095] When the number of times of verification Y exceeds the
second number of times Z (that is, Y>Z) based on the
verification result in Step S860, the reverse current prevention
apparatus 180 performs Step S830 for controlling the switch 131 of
the synchronous rectification circuit 130 to be in the OFF state.
That is, when the accumulated number of times of verification Y
that the output voltage value V1 of the DC-DC converter 100 is
verified to be equal to or greater than the value obtained by
subtracting the error value 0.2 V from the reference output voltage
value V2 and the supply voltage value V3 is verified to be less
than the previous supply voltage value V3_old exceeds the second
number of times Z (that is, Y>Z), the reverse current prevention
apparatus 180 controls the switch 131 of the synchronous
rectification circuit 130 to be in the OFF state. Hereinafter, for
convenience of description, such an operation will be referred to
as a control operation according to Mode 2. As described above,
when the switch 131 of the synchronous rectification circuit 130 is
controlled to be in the OFF state according to Mode 2, an output
current of the DC-DC converter 100, a current of the low voltage
battery 160, the output voltage value V1 of the DC-DC converter
100, the reference output voltage value V2, and the supply voltage
value V3 may be varied as shown in FIG. 6.
[0096] At this point, when controlling the switch 131 of the
synchronous rectification circuit 130 to be in the OFF state
according to Mode 2, the reverse current prevention apparatus 180
determines the previous supply voltage value V3_old to a current
supply voltage value V3 that is calculated using a currently
measured output voltage value V1 of the DC-DC converter 100 and a
currently set reference output voltage value V2 thereof (that is,
V3_old=V3), and then resets the number of times of verification Y
to 0 in Step S830.
[0097] In addition, the reverse current prevention apparatus 180
stores a value (a variation amount of the supply voltage, that is,
.DELTA.V=V3-V3_old), which is obtained by subtracting the prestored
previous supply voltage value V3_old from the supply voltage value
V3 that is determined through the current output voltage value V1
of the DC-DC converter 100 and the reference output voltage value
V2 thereof, in the separate memory. When a previous variation
amount of the supply voltage .DELTA.V_old has been stored in the
separate memory, the controller 183 stores the currently obtained
variation amount of the supply voltage .DELTA.V at the previous
variation amount of the supply voltage .DELTA.V_old (that is,
.DELTA.V_old=.DELTA.V).
[0098] When the current supply voltage value V3 is verified to be
equal to or greater than the previous supply voltage value V3_old
(that is, V3.gtoreq.V3_old) based on the comparison result of the
current supply voltage value V3 and the previous supply voltage
value V3_old and the verification result in Step S840, the reverse
current prevention apparatus 180 controls the switch 131 of the
synchronous rectification circuit 130 to be in an ON state in Step
S870. That is, the reverse current prevention apparatus 180
maintains the ON state when the switch 131 of the synchronous
rectification circuit 130 is previously in the ON state, whereas it
switches the OFF state to the ON state when the switch 131 of the
synchronous rectification circuit 130 is previously in the OFF
state.
[0099] At this point, the reverse current prevention apparatus 180
determines the previous supply voltage value V3_old to the current
supply voltage value V3 that is calculated using the currently
measured output voltage value V1 of the DC-DC converter 100 and the
currently set reference output voltage value V2 thereof (that is,
V3_old=V3). Also, the number of times of operation N and the number
of times of verification Y are reset to 0, respectively.
[0100] In addition, the reverse current prevention apparatus 180
stores a value (a variation amount of the supply voltage, that is,
.DELTA.V=V3-V3_old), which is obtained by subtracting the prestored
previous supply voltage value V3_old from the supply voltage value
V3 that is determined through the current output voltage value V1
of the DC-DC converter 100 and the reference output voltage value
V2, in the separate memory. When a previous variation amount of the
supply voltage .DELTA.V_old has been stored in the separate memory,
the controller 183 stores the currently obtained variation amount
of the supply voltage .DELTA.V at the previous variation amount of
the supply voltage .DELTA.V_old (that is,
.DELTA.V_old=.DELTA.V).
[0101] Meanwhile, when the current supply voltage value V3 is
verified to be less than the previous supply voltage value V3_old
(that is, V3<V3_old) based on of the comparison result of the
current supply voltage value V3 and the previous supply voltage
value V3_old and the verification result in Step S840 to count up
(accumulate) the number of times of verification Y in Step S850,
and the counted (accumulated) number of times of verification Y is
equal to or less than the second number of times Z based on the
verification result in Step S860, the reverse current prevention
apparatus 180 performs Step S870 in which the switch 131 of the
synchronous rectification circuit 130 is controlled to be in the ON
state. Similarly, in this case, the reverse current prevention
apparatus 180 determines the previous supply voltage value V3_old
to the current supply voltage value V3 that is calculated using the
currently measured output voltage value V1 of the DC-DC converter
100 and the currently set reference output voltage value V2 thereof
(that is, V3_old=V3), and resets the number of times of operation N
being counted until now to 0.
[0102] Further, the reverse current prevention apparatus 180 stores
a value (a variation amount of the supply voltage, that is,
.DELTA.V=V3-V3_old), which is obtained by subtracting the prestored
previous supply voltage value V3_old from the supply voltage value
V3 that is determined through the current output voltage value V1
of the DC-DC converter 100 and the reference output voltage value
V2 thereof, in the separate memory. When a previous variation
amount of the supply voltage .DELTA.V_old has been stored in the
separate memory, the controller 183 stores the currently obtained
variation amount of the supply voltage .DELTA.V at the previous
variation amount of the supply voltage .DELTA.V_old (that is,
.DELTA.V_old=.DELTA.V).
[0103] Through the above described process, the reverse current
prevention apparatus 180 may adaptively control the switch 131 of
the synchronous rectification circuit 130 to be in the OFF or ON
state using the output voltage value V1 of the DC-DC converter 100,
the reference output voltage value V2 thereof, and the supply
voltage value V3. For example, voltage levels of the output voltage
value V1 of the DC-DC converter 100, the reference output voltage
value V2 thereof, and the supply voltage value V3 may be shown as
in FIG. 7 according to a state control of the switch 131 of the
synchronous rectification circuit 130 in Mode 1 and Mode 2.
[0104] As described above, in accordance with an exemplary
embodiment of the present invention, generation of a reverse
current in a DC-DC converter of a vehicle may be prevented by
verifying in advance a condition in which the reverse current is
generated and blocking a cause related thereto using variables that
could be verified through a conventional sensing circuit of the
DC-DC converter of a synchronous rectification type in the
vehicle.
[0105] Moreover, in accordance with an exemplary embodiment of the
present invention, a separate hardware circuit is not added or
changed and a sensor for sensing a reverse current is omitted so as
to prevent a reverse current in a DC-DC converter of a vehicle so
that the number of components may be reduced to realize reduction
of manufacturing costs, a simplified process, and weight
reduction.
[0106] The measurement portion 181, verification portion 182 and
controller 183, and/or one or more components of these measurement
portion 181, verification portion 182 and controller 183 may be
implemented via one or more general purpose and/or special purpose
components, such as one or more discrete circuits, digital signal
processing chips, integrated circuits, application specific
integrated circuits, microprocessors, processors, programmable
arrays, field programmable arrays, instruction set processors,
and/or the like. In this manner, the features, functions,
processes, etc., described herein may be implemented via software,
hardware (e.g., general processor, digital signal processing (DSP)
chip, an application specific integrated circuit (ASIC), field
programmable gate arrays (FPGAs), etc.), firmware, or a combination
thereof. As such, the various measurement portion 181, verification
portion 182 and controller 183 and/or one or more components of
thereof may include or otherwise be associated with one or more
memories (not shown) including code (e.g., instructions) configured
to cause the various measurement portion 181, verification portion
182 and controller 183 and/or one or more components of thereof to
perform one or more of the features, functions, processes, etc.,
described herein.
[0107] The memories may be any medium that participates in
providing code to the one or more software, hardware, and/or
firmware components for execution. If implemented in software, the
functions may be stored as one or more instructions or code on a
non-transitory computer-readable medium or non-transitory
processor-readable medium. Such medium or memories may be
implemented in any suitable form, including, but not limited to,
non-volatile media, volatile media, and transmission media.
Non-volatile media include, for example, optical or magnetic disks.
Volatile media include dynamic memory. Transmission media include
coaxial cables, copper wire, and fiber optics. Transmission media
can also take the form of acoustic, optical, or electromagnetic
waves. Common forms of computer-readable media include, for
example, a floppy disk, a flexible disk, hard disk, magnetic tape,
any other magnetic medium, a compact disk-read only memory
(CD-ROM), a rewriteable compact disk (CDRW), a digital video disk
(DVD), a rewriteable DVD (DVD-RW), any other optical medium, punch
cards, paper tape, optical mark sheets, any other physical medium
with patterns of holes or other optically recognizable indicia, a
random-access memory (RAM), a programmable read only memory (PROM),
and erasable programmable read only memory (EPROM), a FLASH-EPROM,
any other memory chip or cartridge, a carrier wave, or any other
medium from which information may be read by, for example, a
controller/processor.
[0108] Although certain exemplary embodiments have been described
with reference to a number of illustrative embodiments thereof, it
should be understood that numerous other modifications and
embodiments can be devised by those skilled in the art without
changing the technical spirit and feature of the principles of this
disclosure. The exemplary embodiments disclosed herein, therefore,
are not to be taken in a sense of limiting the technical concept of
the present invention but as an explanation thereof, and the range
of the technical concept is not limited to these embodiments. The
scope of the present invention should be construed by the appended
claims, along with the full range of alterations or modifications
derived from equivalents to which such claims are entitled.
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